Fire Wreaks Havoc in Mendocino County

Individual vineyards in the Redwood and Potter valleys of Mendocino County are represented by small white circles. The red line shows the perimeter of the Redwood Complex fire currently burning in the area. Image: Mendocino Winegrowers

UPDATED: 10:45 p.m.

San Rafael, Calif.—Winery and vineyard owners prepared for fires to flare up again today, as strong winds were expected to return to California’s North Coast region, which has been plagued by fires since late Sunday.

Mendocino County
Cal Fire’s Mendocino Unit had achieved 5% containment for the 30,000-acre Redwood Complex fire as of 7:47 p.m. The fire already had claimed three lives and 250 single-family residences. The Mendocino Winegrowers trade organization confirmed today that Frey Vineyards, the largest operating U.S. organic and Biodynamic winery, was damaged by the blaze. The family-owned property in Redwood Valley, Calif., produced 245,000 cases of wine per year, according to Wines Vines Analytics.

Steep, wooded slopes bordering the Redwood Complex are making it difficult for firefighting crews to gain footing and make progress containing the fire, according to Glenn McGourty, viticulture and plant science advisor for Lake and Mendocino counties.

McGourty, who writes the column Grounded Grapegrowing for Wines & Vines, said the fire started in Potter Valley and, fueled by dry conditions, winds and low humidity, moved to Redwood Valley in a matter of hours. The two areas are home to 14 wineries producing a combined 1.2 million cases of wine, according to Wines Vines Analytics.

About 70% of the county’s grape crop had been harvested when the fire began Sunday evening, the viticulturist said. Cabernet Sauvignon, Zinfandel, Merlot, Petit Sirah and Carignan were among the varieties still hanging.

According to Mendocino Winegrowers, 38 vineyard properties totaling 900 acres were in the fire zone, and five vineyard properties totaling around 200 acres in Potter Valley were damaged.

While vines themselves are not especially prone to catching fire, McGourty said organic matter on the vineyard floor can catch fire and generate enough heat to scorch vines, causing the water in their vascular systems to boil.

How vines react to fire
California’s native plants are adapted to wildfires, which are part of the natural ecosystem that clears old vegetative material and makes way for new growth. Grapevines planted to wine varieties, however, “are not really adapted to fire in any way,” McGourty said.

Even if fire doesn’t touch grapevines directly, the hot air it creates can be destructive. “It’s surprising how much damage a fire can do if there’s a vineyard nearby,” McGourty said, adding that when there are hot embers blowing on your property, there is not much you can do to stop it. (Read how one vineyard crew held back a fire in Napa Valley here.)

“If you look at the vines right now and everything looks like cornflakes on them, then they are probably damaged,” McGourty explained. “If you have burnt bark around the trunk, you’re going to have trouble with those vines: It’s a given.”

Smoke taint
Even winery and vineyard owners whose properties escaped the fire aren’t completely safe. Residents 100 miles south of Mendocino experienced “snowfall” comprised of ash Monday morning, and an alert from Spare the Air says the air quality Thursday will be in the “very unhealthy” (or worst) category across the Bay Area.

If grapes are bathed in smoke for long enough, they absorb aromas and flavors through their skins. But in spite of university studies and anecdotal evidence, how long it takes for the transformation to occur is still unknown.

“One of the great confusions is: 'How much smoke does it take to affect flavors?'” McGourty said.

Wines & Vines published a roundup of smoke taint research in 2015. And Carmel Valley winemakers detailed their experiences with smoke taint just last year.
Across the North Coast
Total acreage for the 11 fires burning in Napa, Sonoma, Mendocino and Lake counties grew to 139,679 acres today, up from 85,000 acres Tuesday. The swift increase was fueled in part by the Atlas Fire, which grew from 25,000 acres to 42,349 acres overnight and is now 3% contained, and the Partrick Fire, which was just 1,000 acres Tuesday and now stands at 9,523 acres at 2% containment. A new blaze, the Norrbom Fire, broke out around 1:40 p.m. today east of Boyes Hot Springs (Sonoma County) and had grown to 1,831 acres by 4 p.m. and 4,331 acres by 9:51 p.m. These fires are part of the Southern LNU Complex being managed by Cal Fire’s Sonoma-Lake-Napa Unit.

For more information about the fires in California, visit fire.ca.gov.